Shock absorber



J. R. SNYDER SHOCK ABSORBER Aug; 13, 1935.

Filed Marbh 26, 1950 s Sheets-Sheet 1 I MAXJRebounL Aug. 13, 1935. J. R. SNYDER SHOCK ABSORBER Filed March-26, 1930 5 Sheets-Sheet.2

" V I fizz/6 12 5 v Aug. 13, 1935.

J. R. SNYDER SHOCK ABSORBER 3 Sheets-Sheet 3 1?: lien C015 I I m W;

Filed March 26, 1950 Patented Aug. 13, 1935 UNITED STATES PAT E'NT OFFICE SHOCK ABSORBER Jacob R. Snyder, Mount Lebanon, Pa. Application March 26, 1930,,Serial No. 438,987

11 Claims. (01. 188-88) 7 I r v This invention relates to a two-way hydraulic shock absorber, and has for one of' its objects to provide such a device which is simple in construcprovide adjustable means whereby any desired resistance is obtainable for opposing the four movements constituting a cycle of operations.

A further object of the invention is to provide a device of the character referred to which will.

Fig. 21's a transverse vertical sectional view taken on line 22 of Fig. 1.

Fig. 3 is a chart illustrating graphically the cycle ofoperations of the shock absorber embodying the present invention.

Fig. 4 is a fragmentary sectional view showing a reversal of the valve mechanism with respect to the passageways, at one end of the cylinder,-it being understood that the valve mechanism is similarly reversed with respect to the passageways, at the opposite end of the cylinder."

Fig. 5 is a vertical sectional view of the shock absorber, showing a modified arrangement em bodying the invention.

Fig. 6 is a transverse sectional view taken at the upper part'of the shock absorber, and showing the mounting forthe link connection. v

Fi 7 is a transverse sectional view taken on line 1-1 of Fig. 5.

Fig. dis a fragmentary sectional View showing a modified form of the link connection.

Fig. 9 is a vertical sectional view of a shock absorber embodying the present invention in a modified form. V

Fig.- 10 is a transverse sectional view taken on line Ill-l0 of Fig. 9.

In the drawings, the shock absorber is repre-* sented generally by the numeral 20 and consists of a housing 2| of cast iron or other suitable ma-.' terial which has formed integral therewith and at its rear portion an attaching flange '22 provided 5- with transverse openings 23 which are adapted to receive bolts by which the shock absorber isirigidly attached to the chassis of a motor vehicle, in the well known manner. 7

The housing 2i is provided with longitudinally 10* extending, diametrically 'opposite extensions 24" which are provided with axially aligned bores 25'' and 26, the surfaces of which are preferably ma" chined or otherwise suitably finished 'to receive m therein reciprocating pistons-21 and 28 respec- 15"" tively. The outer ends-of the extensions 24 are interiorly screw-threaded to receive screwthreaded plugs 2 9 which, when screwed into place, close the ends of the bores 25and 26 respectively." The connection'between the plugs 29 and the ends 20.; of the extensions 24 are rendered oil-tight means of washers 30. v

The housing 2| adjacent its center portion is provided with a chambert which will be termed" the low pressure chamber and is adapted 'tojre- 25;. i

ceive and retain the necessary amount'fo f fluid, the normal height being indicated by the line 32. This fiuidmay be of any of the well known types employed for this purpose, such as glycerine or any other fluid havingthe proper viscosity. T 130 2 The chamber 3| is enclosed'by a dome or up'.-f wardly extending wall '33 which has; an opening;

34 which is interiorly screw-threaded and adapted.

to receive a screw-threaded'plug 35,. This screw.- threaded plug 35 is disposed directlyabove the 35 1 chamber 3| and is principally provided for the purpose of assembling the shock absorber and for access in case of repair, and the connection between the plug and the dome 33 is rendered. oiltight by a washer 36. i I

Longitudinally extending grooves 31 are. pros vided in the upper portions of the tubular exten? sions 24 adjacent the peripheries of the b'oresf25' and 26 and also adjacent the inner endsof the bores. These grooves 31 are of sufiicient length to 45. overlap the portions of the pistons 21 and 28 as; jacent the grooves and. comunicate with the bores 25 and 26, which will be termed the high pressure; chambers, and the low pressure chamber 3! which contains the main body of oil. It will, therefore, be seenithat the necessary amount of oil is always maintained in the high pressure chambers '25 and.

25, and as the area of these groovesis so small, they do not have any effect upon the efliciency of f the shock absorber.

These pistons 21 and 28 may be of any suitable material cast or otherwise formed, and at their inner adjacent ends are pivotally connected by pins 38 to links 39 which latter have their inner ends pivotally connected by a pin 40 to the depending arms 4| of a yoke 42. The yoke 42 has a transverse bore which receives a pin 43 and to which it is locked against relative rotation by a set-screw 44 which is mounted in the upper portion of the yoke 42 in such a position as to be accessible through the plug 35. One end of the pin 43, the rear end as illustrated in the drawings, is movably supported in a bushing 45 secured within a counterbore 45 provided upon the inner side of the rear wall of the housing, as shown in Fig. 2. The opposite end of the pin 43 is supported within a bushing 41 secured within a transverse opening 48 in the front wall of the housing, as shown in Fig. 2, and to render.

; mentwith a connecting. link secured to the spring or axle in the usual manner. It will therefore be seen. that when the pin 43 is moved in a clockwise. direction,.by reason-o1. the movement of the arm'52, the pistons 21 and 28 will move toward the left, as indicated by the arrow G, this movement representing the rebound stroke between the chassis and the spring ortaxle. when the pin 43 is moved in. a counter-clockwisedirectionby reason of. movement of the arm. 52, the

pistons 21 and 28 will be movedin the direction indicated by the arrow F, this movement representing the compression strokebetween the chas sis and the spring or axle. The relative position of. the pistons 21 and. 28 with respect to the bores 25 and 26 respectively, a s shown in Fig. 1, represents the neutral position of the shock absorber.

' The high pressure chambers 25 and 25 are,

respectively in fluid. communication. through pas sageways 54 and 55 which. extend. longitudinally and at the lowerportion of the housing H. The

passageway 54,- which is shown in full lines in 1, communicates with the high pressurechamber 25 throughfa laterally extending opening 56 which is positioned with respect to the piston. 21' whilein its normal position, as shown in. Fig. I, sothat there is a very slight opening between the outer end of the piston and the end of the opening in the wall. of the extension.

It will therefore be seen that the piston does not only function as such but at the same time operates as a. slide valve with respect. to the opening 55, the purpose of which will be herein-. after more fully described. A passageway. 55 communicates in alike. manner, as explained with respect to the. passageway 54, except that it com.-

municates by a. laterally extending opening 58" with the. high pressure chamber 26, the. position of the openingv 58 havingthe same relation with respect to the piston 28 as does the open;

- ,;ing 56 with respect to the piston 21.

The opposite end of, the passageway .54 communicates with the high pressure chamber 25 through a laterally extending opening 59 which extends throughthe wall of the extension ad- ;fjacent the inner end of the plug 29 or beyond as shown in Fig. 1.

the normal stroke of the piston 23 in the direction indicated by the arrow F. This opening 59 is controlled by a valve which comprises a valve head 68 which engages a valve seat GI provided at the lower end of the opening 59. The valve 60 is maintained in engagement/with its seat 6| by means of a coil spring 62 and is slidably mounted within a centrally extending bore 63 of a screw-threaded plug 64. This plug is adjustably mounted in an extension 55 at the lower portion of the housing 2i andismaintained in adjusted position by means of a lock nut 66, the adjustment of the plug controlling the tension exerted by the spring 62 to maintain the valve in its closed position. The lower end of the valve 5-0 is guided in its movement within the opening 59 by an extension 51 on the end of thevalve, and topermit quick passage of the fluid from the high compression chamber 26 through the valve when it is lifted from its seat, a plurality of transverse openings 68 are provided.

The sleeve 59 of the valve 50 has a transverse opening 10 adjacent the valve head 68' and positioned so as to provide for constant fluid communication between the passageway 54 and. the high compression chamber 26. The flow of fluid through the opening 10 is controlled by means of i a needle valve H which is mounted for move.- mentwithin the sleeve 59 and is adjustable by means of its upper screw-threaded end which is mounted within the screw-threadedplug 54,

This needle valve is, therefore, adjustable longitudinally of the sleeve 69, g

and its lower end being tapered provides for a very fine adiustment to control the flow of fluid. through the opening l0. The needle valve-may be. locked in place by a lock nut '12. u

. As the end of the passageway opposite the lateral. opening 58 is connected through a lateral opening 13 with the high pressure chamber 25 by .means of a-valve 1.4 in precisely thesame manner as the valve 60, and as the needle valve 15 controls the flow of fluid through the opening I6 in the sleeve of the valve 14, in precisely the same manner as the needle valve H controls the passage of low pressure chamber. I

. In'theoperation of the device, we will assume the relationship of the parts to be as shown in Fig. 1, which we will term the neutral positionand which position the parts assume when the shock absorber is properly attached to a motor vehicle.

It should also be understood that the lines', E,.

D, B and A of the chart illustrated in Fig. 3 are indicative of the direction of movement of the end of the arm 52. which is attached to the shock absorber and further represents the relative position of the end of the arm 52 with respect to its neutral position represented by the line N, during the deflection of thespringsand the rebound,

On the compression, stroke where the springs" and axle are causedto move toward the chassis, the piston 28 is moved in the direction indicated by the arrow F. The movement of the piston forces the fluid in the high pressure chamber 25.

through the-opening 59 which unseats the valve against the tension of the spring 62,. thereby permitting the fluid to pass through the passageway 54 and through the opening 55 into the high-pressure chamber 25. The passage of the fiuid into- A pipe the high pressure chamber 25 ispermitted due to the fact that the piston 21 has also been moved to the right past the opening 56 to a position approximating that represented by dotted lines 11. Of course if the deflection of the springs is slight, the movement of the piston 28 willprobably not create sufiicient pressure to unseat the valve 60 and, therefore, the fluid from the high pressure chamber 26 is permitted to flow through the cen tral opening in the valve fifl'and out through the opening in the side wall of sleeve69. The

amount of resistance offered, therefore, to the compression stroke from its neutral position to maximum compression, as represented by the line E, is controlled by placing the spring 62 under the desired tension to resist the unseating of the valve 60.

On the rebound stroke of the operation, represented by the line D and being the return of the spring with respect to the chassis from its maximum compression to neutral position, the piston 21 is caused to move in the direction indicated by the arrow G. As the piston 21 is in the position indicated by the dotted lines 11, the initial movement of the piston in the direction of the arrow 7 G forces the liquid in the high pressure chamber through the opening 56.

This fluid then passes through the passageway 54, andas it cannot pass by the valve 60, it is'permitte'd to pass through the opening 10 in the sleeve 69and thence through the central opening in the sleeve and into the high compression chamber 26. The resistance to this movement of the piston 21 is therefore con- I trolled by the needle valve H, the latter being adjustable so as to control the flow of fluid throughthe opening 10, and thus any desired resistance tothis stroke may be obtained. At the end of this stroke, the piston 21 has returned to its neutral position, as represented by full lines in unseats the valve 14 against the tension of the spring 19, thus permitting the fluid toflow past the valve and through the passageway 55; The fluid then passes outwardly through the opening '58 into the high pressure chamber 26 inasmuch as the piston 28 has been moved to the'left until it is positioned beyond the opening 58 similar to that represented bythe dotted lines TI. The resistance ofiered to this stroke, therefore, can be controlled by varying the tension of the spring 19, and by such adjustment it is therefore possible to obtain 1 any degree-of resistance desired.

Upon the return stroke of the springs with respect to the chassis from the maximum rebound position to its neutral position, as indicated by the line A of the chart, the piston 28 is moved in the direction indicated by the arrow F and such movement of the piston causes the fluid in the high pressure chamber 26 to flow through the opening 58. The fluid then passes through the passageway 55, and as it cannot pass the valve 14, it is caused to pass through the opening 16 in the sleeve of the valve and through the central opening into the high pressure chamber 25. The

resistance to the passage of fluid through. the

opening 16 is controlled by the needle valve so that it is possible to obtain any degree of resistance desired.

Y From the foregoing description of the operation and construction of the shock absorber embody ing the'present invention, it is to be pointed out that oneof the important features of the invention is to be able to obtain any desired resistance to the compression strokes and the rebound.

strokes between the springs and chassis of the motor vehicle. For example, referring again to the chart in Fig. '3, it might be desired to offer to the movement of the piston of the shock absorber from neutral to maximum compression, a resistance of '75, while from maximum compression back to neutral a resistance of 25, due to the fact that it would probably not be desirable to retard the movement of the springs and chassis from maximum compression back to neutral as much as it would be desirable to counteract the movement from neutral to maximum compression. The same is true with checking the movement from neutral to maximum rebound which would indicatethe movement of the springs away from the chassis to its maximum position. "This resistance might be represented by 100 so as to prevent bottoming and then the return from maximum rebound to neutral might have a resistance of so as to -gradually resist the return of the springs to-neutral position.

In Figs. 5, 6, and 7 there is illustrated a, modification of the invention embodied in the shock absorber to the extent that a single reciprocating piston is employed between the high pressure chambers. Aside from this change, the operation of the shock absorber isprecisely the same as that already explained with respect to Fig. '1.

A housing 88 of any suitable material, such as cast iron, is provided with a bore 8|, which has disposedtherein, and adapted to be reciprocated back and forth, a piston 82 which divides the bore 8! into a pair of high pressure fluid chambers 83 and 84 respectively, for a purpose to be later described. 1 g

The piston 82 is formed preferably integral with a tubular member 85, the lower end of which is slidably mounted within an opening 86 coaxial with the bore 8 I, while the upper end of the tubular member is'slidably mounted within a bushing 87, suitably secured within a transverse opening in a ring 88. The ring 88 is exteriorly screw threaded and cooperates with the interior screw 1 threads providedadjacent the upper portion of the bore 8 l This ring 88 may be secured in place by a set screw 89which is mounted within the wall of the housing 80.

, At the lowerportion of the housing 80 there is a low pressure chamber '90, while at the upper portion of the housing there is a low pressure chamber 9|, which serves as a reservoir for any suitable operating fluid which is supplied to the chambers! through a pipe 92, or other suitable means. communication with the low pressure chamber 9| through the longitudinally extending opening in The upper end of the.

the tubular member 85. housing 80 is open and receives a cover 93, which is held in place by bolts 94 so as to close the opening but at the same time permits access there through for thepurpose of inspecting the working parts of the shock absorber, and for the purpose of ready assembly.

The piston 82 is reciprocated back and forth by a link connection 95, pivotally connected at 96 to the upper end of the tubular member 85,

The low pressure chamber is in fluid through the front wall of the I pressure chamber 83.

for connection with the axle or spring of and at the opposite end connected to the transversely extending shaft or pin 91'. -A-set screw 93 is carried by the link connection 95 and engages witha suitable opening in the shaft or pin 9'! toprevent relative rotation therebetween. One

end of the shaft or pin 911s rotatably supported in an opening 99 provided in the rear wall of the housing 80, while the opposite end of the shaftor pin 9? is mounted within a bushing I00 secured within. a transverse opening IIJI extending housing 80, as

clearly shown in Fig. 6. I I

A' connecting arm I02 has one end mounted upon the outer end of the pin or shaft 91, and is secured againstrelative rotation by a'set screw I03. The opposite end of the arm I02 is adapted motor vehicle by any suitable means.

The high pressure chambers 83 and M are in fluid communication by means of passageways I 04' and H35 respectively. The passageway I04.

has a laterally extending opening I05, which communicates with the high pressure chamber 83,. and aiaterally extending opening III'I which com inunicates with the high pressure chamber 84.: Thepassageway I95 has a laterally extending opening I08, which communicates with the highv pressure chamber 84 and a laterally extending opening I09 which communicates with the-high The laterally extending openings I96 and-08- are positioned in definite relationshipwith respect to the piston 82,- as

shown in Fig. 5, and their positioning should be such thatwhen the piston is r'eciprocated, one of theopenings is closed-thereby,-and the other opening is open, and vice versa. f

. The transverse opening IE1 is normally closed by a valve I It, which is maintained in closed posi- The tension of this tiontby a coil-spring III. spring I I I is varied by a screw-threaded plug I I2 mounted within the housing- The sleeve of the valve IIG has a laterally extending opening II3 extending therethrough for the flow of fluid,

and the size of the opening is variable by means to the valve I It, it is believed that furtherexplanation is unnecessary.

In the operation of this device as shown in the modified form in Fig. 5, the fluid is forced from one. high pressure chamber to the other high pressure chamber, depending'upon the direction of movement of the piston 82. The fluid passes through the passageways I04 and I05, and

the resistance to thefiow of fluid is controlled by the spring actuated valves I III and H5, as well as.

the needle valves H4 and IIS. It will therefore be seen that when the piston 82 moves in one. direction, the flow of fluid is resiliently or yield-.

ingly resisted by means of the spring actuated valves, and when moved in the opposite direction 3 the flow of fluidis rig'idlyresisted during the initial movement-of the piston bymeans of the needle valves. It will therefore be seen that the desired resistances offered to the flow of fluid between the high pressure chambers are obtained by adjustability of the valves, so that where it or shaft .91.

great an extent as possible, mechanical joints and; connections which ordinarily become noisyfafterthe is desired, different resistancesv are, obtainable with respect to the fourjoperating conditionsas explained with reference to the chart illustrated, inFig.3. 3 I 1" v A check valve -I I1 is provided in the ring 88.

and permits; the fluid tofl'ow from the lowlpressure chamber 9I intothe highpressure chamber 84,, When the fiuidin the high pressure chambers.

has diminished for anyreason whatsoever In Fig. 8 there is illustrated a modifiedform of. link connection between the piston 82 and the pin It is advisable to eliminate to as:

being in operation for a considerable length-0f.

time The upper-portion of the tubular member; is provided with a laterally extending flange H8, through which extends the stem of a Tmember I I9. member I I9 and the flange I I8, is a rubberwasher I20, and a second rubber washer-IZI ispositioned:

in contact with the head: of the T member I19, but on the opposite side thereof; A pair of. lock screws: I22 cooperate with screw threads proand when turned into'place tend to'maintain the Disposed between the-head of; the T- T member ,I I9 in assembled relation with respect to the rubber Washers I20- and -I2I.

ber 85. I An arm I25,which is I26.- positev sides ofthe rubb'er- Washers I26, and are rigidly held in assembled relationby a member:

I28 which is pinned or otherwise secured to the free endof the T member '9. ,It 'will'be' noted that there :isno metal to metal contact between the movable parts and that universal movement ispermitted due'to the resiliency of the rubber washers.

"Referring now the same invention. A housing I28 of anysuitable material, such as cast iron, is provided with.

a pair of parallel bores I29. and I30 respectively:

The bores are open at theirupper ends but are closed at their lower ends by transversely ex tending wall or partition I3I A pair ofpistons Centrally. aligned openings I23 extend through the-locking, members I22, the rubber washer 'I2'I 'andpart of. the; T member H9 and communicate .with; a; transverse opening I24,"thus permitting the passage of fluid from the low pressure chamber fil" throughthe central opening ofthe tubular. memsecured by the set screw 88;to the shaft or pin 91, has, its opposite sides. counterbored to receive a pair of rubber blocks A pair of washers I21. engage with the 011-.

I to Figs. 9 and 10, there is dis -v closed astill further Jmodification of the struc-- ture of the shock absorber but still embodying t I32 and I33 respectively, all substantially U-f shaped in cross section, are reciprocably disposed within the bores I29 and I30, and, when so as.-;

sembled provide a pair of high pressure fluid chambers I34 and l'35 respectively. .These pis tons I32 and I33 arenormally maintained inelevated positionby means of coil springs I36, one;

end of which is disposed within the pistons and engages the closed ends thereof, while the op posite ends engage circular bosses I31 provided .upon the upper surfaceof the' transverse parti =ti0n I3I. i

The pistons I32 and I33 are reciprocated with-'v in the bores I29 and I3!) respectively, by means.

of a rocker arm I38, which is secured by aset screw I39 to the transverse shaft or pin 140.3 This rocker arm has extensions I4I provided with rounded surfaces which engage the closed ends of V the pistons I32 and I33.. Therefore, whenthe.

vided upon the interior of the tubular member 85, 7

movement of the shaft I45 about its axis. 'willbe further noted that when one piston is shaft or pin III) is moved about its axis, the endslgstroke the arm I38 would be moved in a clock- Wise position, causing the piston I33 to be de- I4I oi the rocker arm I38, will cause the pistons to move longitudinally against the. resistance ofthe. springs I35, depending upon the direction of t depressed against the tension of the spring, the other piston is moved in an opposite direction by the tension of its cooperating spring, so that alternate rocking of the rocker arm I33 causes the pistons I32 and I33 to be reciprocated alternately.

One end of the shaft I45 is journaled within a -bllShlllg I42 carried by a screw threaded plug I43 in the rear wall of the bushing, while the other end is mounted within a bushing I44, disposed within an opening in the front wall of the housing, such as shown in Fig. 10. A suitable gasket I55 surrounds the shaft I45 and is held in rigid engagement with the "end of the bushing I44 by means of a screw threaded sleeve I55, to thereby prevent the passage of fluid along the shaft I40. An operating arm HIT has one end connected to the outer end of the shaft I45 by a set screw I 58, while its other end is adapted for connection with the axle or springs of a motor v vehicle by any suitable means.

A passageway I49 extends throughthe housing I28, and communicates with the high pressure chamber I35 through a laterally extending opening I55, while the opposite end communicates with the high pressure chamber I35 through an opening I5I extending centrally through the transverse partition I3I and the circular boss I37. A second passageway I52 communicates with the high pressure chamber I35, through a laterally extending opening I53, while the opposite end are mounted within the housing I23, and

operate with the openings I 54 and II respectively. As the construction and operation of the valve mechanisms are identical with the con struction and operation of the valve 58 of Fig. 1,

it is believed that further detailed description with respect to the operation and construction of the valve mechanisms I55 and I55, will be unnecessary, but reference to the operation of the valve mechanism in Fig. 1 may be resorted to for a more detailed explanation, if found desirable.

In the operation of the device when properly attached between the chassis and springs or axle of a motor vehicle, upon the compression stroke, the-piston I32 would be depressed by movement of the rocker arm I38 against the tension of the spring I36, while the piston I 33'would be raised by the tension of the spring I35, due to the counterclockwise movement of the arm I38. The depressing of the piston I32, would cause the fluid in the high pressure chamber I34 to flow through the opening I54, thereby removing the valve'from its seat against the tension of the spring. The fluid would then pass through the passageway I52, and into the high pressure chamber I35, through the laterally extending opening I53. This is made possible by the fact that the piston I33 has been elevated so as to expose the opening I53. The valve mechanism I55, therefore offers, as in the case of the construction disclosed in Fig. l, a yielding resistance to the flow of fluid from the high pressure chamber I34 to the high pressure chamber I35. On the rebound pressed against the tension of the spring I35.

fluid in the high pressure chamber I to flow through the laterally extending opening I53 into the passageway I52, and through the transverse opening in the sleeve of the valve I55. This opening, as before stated, is controlledby anecdle valve, and thereby the flow of fluid therethrough, is fixedly resisted; Further depression of the piston I33 causes the opening I53 to be closed thereby, and thefluid within the high pressure chamber I35 passes through the opening I5I and unseats the valve of the valve mechanism I55. The fluid is then permitted to pass by the valve into the passageway I59, and through the laterally extending opening I50, into the high pressure chamber I34. This is possible due to the fact that the piston I32 has been elevated by the tension of the spring I35, which is made possible by the clockwise rotation of the rocker arm I38. It will, therefore, be noted that the flow of fluid through the passageway I59 is yieldably resisted'due to the. spring controlled valve mechanism I55. Upon the initial movement of the piston I32 in its downward movement, the fluid in the high pressure chamber I34" is. first forced outwardly through the laterally extending opening I55, through the passageway Hi3, and through the transverse opening in the sleeve of. the valve of the valve mechanism I 55. This opening is controlled by the needle valve as before described,

I34 to the high pressure chamber I35.

As previously stated, the tension of the springs of the valve mechanism I and I55 maybe varied so as to obtain any desired resistancev to the flow of fluid thereby, as well as adjustment of the needle valves for the same purpose.

Fig. 4 illustrates a modification of the construction of the shock absorber embodying the present invention wherein the valve mechanism 14 may be associated with the transverse opening 55 for controlling the flow of fluid therethrough between the high pressure chambers in which instance the transverse opening I3 as normally valve controlled, as shown in Fig. 1, has the valve mechanism dispensed with. The transand thereby a fixed resistance is presented to the flow of fluid through the high pressurechamber verse opening I3 therefore communicates with the passageway 55 directly with the high pressure chamber 26. It is thereforeto be understood that it is contemplated as coming within the terms of the invention to rearrange the valve mechanisms in any manner which may be desired so as to obtain the desired relative resistances to the four cycles of operation of the shock abone chamber to the other through said conducting means, and means offering a fixed resistance to the flow of fluid during the initial movement of said reciprocable means and a yielding resistance during a further movement thereof in the same direction. I

' 2; In a hydraulic shock absorber, a pair of fluid chambers, fluid conducting .means connecting said chambers, .means for forcing the fluid from one chamber to the other through said conducting means, means ofiering a yielding resistance to the flow of fluid during the initial movement in one direction and a fixed resistance to the flow of fluid in the further movement in the same direction, and means for adjusting the last mentioned means whereby any desired resistance may be obtained. I

' 3. In a hydraulic shock absorber, a pair of fluid chambers, a plurality of passageways having their opposite ends connecting said chambers, means for forcing the fluid from one chamber to the other through saidpassageways, and means to the flow of fluid in the opposite direction through one of said passageways, and means offering .a fixed resistance to the flow of fluid in one direction and a yielding resistance to the .flow of fluid in the opposite direction through the other of said passageways.

5. In a hydraulic shock absorber, a pair of fluid chambers, passageways having their opposite ends connecting said chambers, means for forcing the fluid from one chamber to the other through said passageways, and means offering first a fixed resistance and subsequently a .yield ing resistance to the flow of fluid in one direc- .tion from one chamber to the other.

6. In a hydraulic shock absorber, .a pair of fluid chambers, passageways having their opposit/e ends connecting said chambers, means for forcing the fluid from one chamber to the other through said passageways, means offering a yielding resistance to the flow of fluid in one direction. and a fixed resistance to the flow of fluid in the opposite'direction, and adjustable means for varying the yielding resistance.

7. In a hydraulic shock absorber, a pair of fluid chambers, passageways having their opposite ends connecting said chambers, reciprocable means for forcing the fluid from one chamber to the. other through said I passageways, means ofiering a yielding resistance to the flow of fluid in one direction and a fixed resistance to the flow of fluid in the opposite direction, and adjustable means for varying the fixed resistance.

8. In a hydraulic shock absorber, a pair of means offering a yielding resistance to the flow of fluid in one direction and a. fixed resistance to the flow of fluid in the opposite direction, and adjustable means for varying the yielding and fixedresistances.

9; In a hydraulic shock absorber,- a pair of fluid chambers, passageways connecting said chambers, means for forcing the fluid from one chamber to the other through said passageways, means offering a fixed resistance to the flow 0f fluid in one direction through one passageway, said flow being cut off by movement of said, fluid forcing means, and means subsequently offering a yielding resistance to said flow of fluid in the same direction through the other passageway.

a neutral position to maximum travel in opposite directions and return, comprising means operaatively connected to one of the movable members and movable thereby, means for supporting said movable means and connected with the other of said movable members, means ofiering different resistances to the movements of said movable members from neutral position to maximum travel away therefrom, and means offering different fixed resistances to the movements of said movable members from maximum travel to neutral position.

11. A shock absorber for resisting the relative movements between two movable members from 10. A shock absorber for resisting the relative movements between two movable members from a neutralposition to maximum travel in opposite said movable members, and means offering yielding resistances to the movements 'of :said movable members from neutral position to maximum travel and fixed resistances from maximum travel to neutral position.

JACOB R. SNYDER. 

